Visually, we see meteors because of the heat generated through ram
pressure as the particles fly through the atmosphere. The heat causes
the stripping of electrons from atoms in the atmosphere producing a
trail of ionised gas in the wake of the meteor. This ionised gas acts
like a mirror to radio waves and transmissions from the ground, which
would normally pass out of the atmosphere and into space, are instead
reflected back down to the ground.

In order to detect meteors with radio waves, astronomers in the 1950s
used radar equipment. They sent radio transmissions up into the sky and
then listened for the reflected echoes in a technique known as
back-scatter. Using these echoes, the astronomers could determine the
range and speed of the meteors and then calculate an orbit.

A modern experiment to look for echoes from ionised meteor trails uses a
similar technique, but relys on someone else to be the transmitter.
This technique is known as forward-scatter. The antenna shown in the
image (left) is a simple dipole which listens for signals from a
television station which is too far away to detect normally. When there
is a patch of ionised air created by a meteor, the signal gets reflected
back down to the Earth and can be picked up by the receiver situated, in
this case, at Jodrell Bank Observatory in the UK.

The equipment is simple: a basic dipole, a commercial scanning receiver
and a small amplifier. Each time an echo happens, the scanner produces
a "ping". The sound is fed into the soundcard of a computer where a
graphical representation is generated and the reflections are counted.
This technique, used by amateur astronomers around the world, can detect
meteors 24 hours a day, 365 days a year.